/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.table.types.logical;

import org.apache.flink.annotation.Internal;
import org.apache.flink.annotation.PublicEvolving;
import org.apache.flink.table.api.ValidationException;

import java.util.Collections;
import java.util.List;
import java.util.Objects;
import java.util.Set;

/**
 * Logical type of a timestamp WITHOUT time zone consisting of {@code year-month-day hour:minute:second[.fractional]}
 * with up to nanosecond precision and values ranging from {@code 0000-01-01 00:00:00.000000000} to
 * {@code 9999-12-31 23:59:59.999999999}. Compared to the SQL standard, leap seconds (23:59:60 and 23:59:61)
 * are not supported as the semantics are closer to {@link java.time.LocalDateTime}.
 *
 * <p>The serialized string representation is {@code TIMESTAMP(p)} where {@code p} is the number of
 * digits of fractional seconds (=precision). {@code p} must have a value between 0 and 9 (both inclusive).
 * If no precision is specified, {@code p} is equal to 6. {@code TIMESTAMP(p) WITHOUT TIME ZONE} is a
 * synonym for this type.
 *
 * <p>A conversion from and to {@code long} is not supported as this would imply a time zone. However,
 * this type is time zone free. For more {@link java.time.Instant}-like semantics use
 * {@link LocalZonedTimestampType}.
 *
 * @see ZonedTimestampType
 * @see LocalZonedTimestampType
 */
@PublicEvolving
public final class TimestampType extends LogicalType {

	public static final int MIN_PRECISION = 0;

	public static final int MAX_PRECISION = 9;

	public static final int DEFAULT_PRECISION = 6;

	private static final String FORMAT = "TIMESTAMP(%d)";

	private static final Set<String> INPUT_OUTPUT_CONVERSION = conversionSet(
		java.sql.Timestamp.class.getName(),
		java.time.LocalDateTime.class.getName(),
		"org.apache.flink.table.dataformat.SqlTimestamp");

	private static final Class<?> DEFAULT_CONVERSION = java.time.LocalDateTime.class;

	private final TimestampKind kind;

	private final int precision;

	/**
	 * Internal constructor that allows attaching additional metadata about time attribute
	 * properties. The additional metadata does not affect equality or serializability.
	 *
	 * <p>Use {@link #getKind()} for comparing this metadata.
	 */
	@Internal
	public TimestampType(boolean isNullable, TimestampKind kind, int precision) {
		super(isNullable, LogicalTypeRoot.TIMESTAMP_WITHOUT_TIME_ZONE);
		if (precision < MIN_PRECISION || precision > MAX_PRECISION) {
			throw new ValidationException(
				String.format(
					"Timestamp precision must be between %d and %d (both inclusive).",
					MIN_PRECISION,
					MAX_PRECISION));
		}
		this.kind = kind;
		this.precision = precision;
	}

	public TimestampType(boolean isNullable, int precision) {
		this(isNullable, TimestampKind.REGULAR, precision);
	}

	public TimestampType(int precision) {
		this(true, precision);
	}

	public TimestampType() {
		this(DEFAULT_PRECISION);
	}

	@Internal
	public TimestampKind getKind() {
		return kind;
	}

	public int getPrecision() {
		return precision;
	}

	@Override
	public LogicalType copy(boolean isNullable) {
		return new TimestampType(isNullable, kind, precision);
	}

	@Override
	public String asSerializableString() {
		return withNullability(FORMAT, precision);
	}

	@Override
	public String asSummaryString() {
		if (kind != TimestampKind.REGULAR) {
			return String.format("%s *%s*", asSerializableString(), kind);
		}
		return asSerializableString();
	}

	@Override
	public boolean supportsInputConversion(Class<?> clazz) {
		return INPUT_OUTPUT_CONVERSION.contains(clazz.getName());
	}

	@Override
	public boolean supportsOutputConversion(Class<?> clazz) {
		return INPUT_OUTPUT_CONVERSION.contains(clazz.getName());
	}

	@Override
	public Class<?> getDefaultConversion() {
		return DEFAULT_CONVERSION;
	}

	@Override
	public List<LogicalType> getChildren() {
		return Collections.emptyList();
	}

	@Override
	public <R> R accept(LogicalTypeVisitor<R> visitor) {
		return visitor.visit(this);
	}

	@Override
	public boolean equals(Object o) {
		if (this == o) {
			return true;
		}
		if (o == null || getClass() != o.getClass()) {
			return false;
		}
		if (!super.equals(o)) {
			return false;
		}
		TimestampType that = (TimestampType) o;
		return precision == that.precision;
	}

	@Override
	public int hashCode() {
		return Objects.hash(super.hashCode(), precision);
	}
}
